In some wireless communication systems, user equipments (UEs) wirelessly communicate with one or more base stations. A wireless communication from a UE to a base station is referred to as an uplink communication. A wireless communication from a base station to a UE is referred to as a downlink communication. Resources are required to perform uplink and downlink communications. For example, a base station may wirelessly transmit data to a UE in a downlink communication at a particular frequency for a particular duration of time. The frequency and time duration are examples of resources.
A base station allocates resources for downlink communications to the UEs served by the base station. The downlink communications may be performed by transmitting orthogonal frequency-division multiplexing (OFDM) symbols.
Some UEs served by a base station may need to receive data from the base station with lower latency than other UEs served by the base station. For example, a base station may serve multiple UEs, including a first UE and a second UE. The first UE may be a mobile device carried by a human who is using the first UE to browse on the Internet. The second UE may be equipment on an autonomous vehicle driving on a highway. Although the base station is serving both UEs, the second UE may need to receive data with lower latency compared to the first UE. The second UE may also need to receive its data with higher reliability than the first UE. The second UE may be an ultra-reliable low latency communication (URLLC) UE, whereas the first UE may be an enhanced mobile broadband (eMBB) UE.
UEs that are served by a base station and that require lower latency downlink communication will be referred to as “low latency UEs”. The other UEs served by the base station will be referred to as a “latency tolerant UEs”. Data to be transmitted from the base station to a low latency UE will be referred to as “low latency data”, and data to be transmitted from the base station to a latency tolerant UE will be referred to as “latency tolerant data”. A single UE may use both low latency communication and latency tolerant communication, in which case the term “low latency UE” would refer to the activities of the single UE for the purpose of low latency communication, and the term “latency tolerant UE” would refer to the activities of the single UE for the purpose of latency tolerant communication.
It is desired to have a base station and frame structure that can accommodate the use of the same time-frequency resources by both low latency UEs and latency tolerant UEs.